There is a need to prepare high molecular weight (e.g., high Mooney Viscosity), oil-extended, high molecular weight (for example, Mw>200,000 g/mole) ethylene-based polymers that can be successfully isolated from the polymerization reactor. Polymerization processes of the art are described in the following references: U.S. Pat. Nos. 7,910,637; 7,985,804; 5,516,849; 6,686,419; 6,545,088; 3,726,843; U.S. Provisional 62/097,268 (filed Dec. 29, 2014); International Publication Nos. WO2013/096573; WO2014/003857. See also, P. S. Ravishankar et al., treatise on EPDM, Rubber Chemistry and Technology, Vol. 85, No. 3, pp 327-349, 2012; P. S. Ravishankar et al., Recent Advances in EPDM and Dynamically Vulcanized Thermoplastic Elastomers, 186th Technical Meeting of Rubber Division, ACS, Nashville, Tenn., 2014; pp. 1-15. However, as discussed above, there remains a need to prepare high molecular weight ethylene-based polymers, which can be readily isolated from the polymerization process. These needs have been met by the following invention.